This invention relates to a force-retarding device for a stationary bicycle, particularly to one improved to produce almost no vibration or noise in pedaling a stationary bicycle, and subsequently to prolong service life of the stationary bicycle.
A conventional force-retarding device for a stationary bicycle is shown in FIG. 1, containing a supporting base 10, a flywheel 20 mounted on the supporting base 10, a transmitting element 30 (such as a multi-grooved belt wheel) fixed with one side of the flywheel 20, and a shaft 40 with which are pivotally combined the flywheel 20 and the transmitting element 30 at the same time. Further, a plurality of permanent magnets 201 are equidistantly fixed on the inner annular surface of the flywheel 20, facing a silicon sheet stator 202 wound with coils immovably fixed with the supporting base 10. So when the flywheel 20 is rotated together with the transmitting element 30, the permanent magnets 201 rotate against the stator 202, with induction force produced between the magnets 201 and the stator 202. And the speed alteration of the flywheel 20 in rotation controls the volume of electric current and further controls the torque of the transmitting element 30. Then the torque forms the force-retarding action against pedaling of the stationary bicycle, obtaining effect of health improving exercise by pedaling.
However, the conventional force-retarding device for a stationary bicycle has been found to often give rise to vibration and noise in pedaling the stationary bicycle. After deep research, the cause of the problem has been found the way of positioning of the flywheel 20, which needs two bearings 50 deposited between the transmitting element 30 and the shaft 40 to enable the flywheel 20 together with the transmitting element 30 to rotate on the shaft 40 smoothly. As shown in FIG. 1, to position the bearings 50, C-shaped retain rings 50 are used to secure the outer surface of the bearings 50. Nevertheless, the C-shaped rings 50 may often have error in its thickness, say 0.1-0.2 mm, so that a 0.1-0.2 mm gap may be formed after the C-shaped retain rings 501 are fixed with the bearings 50. Then the result is that the bearings 50 may slide right and left, colliding with and rubbing the C-shaped retain rings 50 or other components when the flywheel 20 together with the transmitting element 30 rotates. Therefore, vibration and noise may arise in pedaling the stationary bicycle, with the colliding condition just mentioned above possibly breaking the C-shaped retain rings 50 in case of light colliding, or with the life of the bearings 50 shortened in case of serious colliding. In addition, there is another problem of insufficient loading force of the shaft 40 having only 15 mm diameter.
The purpose of the invention is to offer a force-retarding device for a stationary bicycle, which produces very little vibration or noise in pedaling it so as to prolong its service life.
The feature of the invention is a movement-stopping base provided between a flywheel and a transmitting element, both of which are pivotally combined on a shaft, and the movement-stopping base has an annular contact surface on which a first bearing, a separating ring and a second bearing are orderly mounted. Outside The second bearing an annular sealer is screwed on an inner surface of the transmitting element, pressing the second bearing, the separating ring and the first bearing toward the movement-stopping base so that there remains almost no gap between any of these components, and consequently no vibration or noise may be produced by the force-retarding device in pedaling the stationary bicycle.